AWWA JAW34956

Laboratory-scale filtration experiments were conducted using sedimentation basin effluent from a local lime-softening water treatment plant. An electronic particle counter was used to observe changes in the particle size distribution of the filtrate as a function of filter depth and time under a variety of filter operating conditions. The experiments were conducted for an extended period (up to 48 h) to observe the effects of both ripening and breakthrough over the duration of a typical water treatment plant filter cycle. The results indicate that ripening and breakthrough are not distinct stages but occur simultaneously for different-size particles. The effects of media size and filtration velocity were investigated, and simple normalizations were developed. Includes 31 references, table, figures.